Add instrumentation (issue 22572)

pkg/analyzer/lib/task/model.dart

Index: pkg/analyzer/lib/task/model.dart
diff --git a/pkg/analyzer/lib/task/model.dart b/pkg/analyzer/lib/task/model.dart
index 3fd8ddb8fb733eda8c13b8d11bb56bb1bede0a79..79c922091cba7666a967a87190e6808050ff4174 100644
--- a/pkg/analyzer/lib/task/model.dart
+++ b/pkg/analyzer/lib/task/model.dart
@@ -170,6 +170,19 @@ abstract class AnalysisTask {
    */
   void _safelyPerform() {
     try {
+      //
+      // Report that this task is being performed.
+      //
+      String contextName = context.name;
+      if (contextName == null) {
+        contextName = 'unnamed';
+      }
+      AnalysisEngine.instance.instrumentationService.logAnalysisTask(
+          contextName,
+          description);
+      //
+      // Gather statistics on the performance of the task.
+      //
       int count = countMap[runtimeType];
       countMap[runtimeType] = count == null ? 1 : count + 1;
       Stopwatch stopwatch = stopwatchMap[runtimeType];
@@ -178,6 +191,9 @@ abstract class AnalysisTask {
         stopwatchMap[runtimeType] = stopwatch;
       }
       stopwatch.start();
+      //
+      // Actually perform the task.
+      //
       try {
         internalPerform();
       } finally {